Experimental investigation of the surface expression of a canopy-induced shear instability
Abstract/Contents
- Abstract
- Submerged vegetation is a critical component of the nearshore environment, having significant effects on coastal protection and estuarine channel evolution, and providing habitat for many economically and ecologically important species including endangered marine mammals. Field studies of submerged vegetated canopies are often expensive and difficult due to reliance on point sensors that directly access the water column. Remote sensing using whole field imaging offers the potential to overcome the limitations of in situ point sensors. However, in environments strongly impacted by human interaction, remote imaging is typically limited to the free surface. To take advantage of the opportunities presented by remote imaging, we must develop a more robust understanding of the mechanisms governing the surface expression of interactions between flow and vegetation. The body of this dissertation is presented in three main chapters. Each chapter presents the results of a series of experimental investigations into the free surface dynamics of channel flows interacting with a submerged array of rigid cylinders which act as a laboratory analog for submerged vegetated canopies. In Chapter II, the instability of the canopy-induced shear layer is proposed as a potential mechanism by which submerged canopies can be detected, and some of their properties inferred, from observations of the turbulence in the near-surface velocity. The properties of this instability signal as manifest on the free surface are explored, and the limitations on detection quantified. Chapter III presents of the results of experiments using laser refractometry and free surface synthetic Schlieren imaging to demonstrate that the dynamics uncovered in the near-surface turbulent velocity field are correspondingly present in the surface slope field, indicating that the instability signal is actually manifest in free surface dynamics. The spectral differences between the instability signal and some other sources of surface distortion, including wave-like ripples and wind chop, are also discussed. Finally, Chapter IV explores the spatially varying behavior of the instability signal along the length of a submerged canopy patch. It is hoped that this work will provide a fruitful foundation on which a remote sensing platform for the detection and monitoring of sensitive submerged vegetative canopies can be built.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2017 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Rosenzweig, Itay |
|---|---|
| Associated with | Stanford University, Civil & Environmental Engineering Department. |
| Primary advisor | Koseff, Jeffrey Russell |
| Thesis advisor | Koseff, Jeffrey Russell |
| Thesis advisor | Fong, Derek |
| Thesis advisor | Fringer, Oliver B. (Oliver Bartlett) |
| Advisor | Fong, Derek |
| Advisor | Fringer, Oliver B. (Oliver Bartlett) |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Itay Rosenzweig. |
|---|---|
| Note | Submitted to the Department of Civil and Environmental Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2017. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2017 by Itay Rosenzweig
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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